The OWTChart Engine produces GIF images of virtually any type of chart from a set of input parameters.
The program can be used as a CGI in a web server environment, in which case it will return a GIF image with the chart built from the parameters found in the QUERY_STRING part of the URL, or from the body of a POST request.
It can also be used as a command-line program. In this case, the chart parameters will be read from a simple text file in which each line contains one parameter in the form "Name=Value", and the output will go to a .GIF file.
OWTChart is Open Source, which means that it can be used freely, for personnal or commercial application, as long as the authors' Copyright and Distribution terms are respected. It is based on the GDChart library, which in turn uses Boutell.com's GD (GifDraw) library.
The OWTChart engine itself has been partly developed under contract with Health Canada as part of the Disease Surveillance On-Line project.